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Bug #3031

ofono: wrong first DNS reported in log

Added by pespin 3 months ago. Updated 3 months ago.

Status:
New
Priority:
Normal
Assignee:
Target version:
-
Start date:
03/04/2018
Due date:
% Done:

0%

Spec Reference:

Description

I saw in a test that once the context is attached successfully, ofono prints the properties:

/sierra_2: context activated {apn='inet46', path='/sierra_2/context2', properties={AccessPointName='inet46', Active=True, AuthenticationMethod='chap', IPv6.Settings={}, Name='Internet', Password='', Protocol='ip', Settings={Address='176.16.46.1', DomainNameServers=['8.8.8.8', '8.8.8.8'], Gateway='176.16.46.2', Interface='wwan1', Method='static', Netmask='255.255.255.252'}, Type='internet', Username='ogt'}, user='ogt'}

However, osmo-ggsn config for that IP states 1st DNS server is 192.168.0.1 instead of 8.8.8.8:

 apn inet46
  gtpu-mode tun
  tun-device tun46
  type-support v4v6
  ip prefix dynamic 176.16.46.0/24
  ip dns 0 192.168.100.1
  ip dns 1 8.8.8.8
  ip ifconfig 176.16.46.0/24
  ipv6 prefix dynamic fde4:8dba:82e1:2000:0:0:0:0/56
  ipv6 dns 0 2001:4860:4860::8888
  ipv6 dns 1 2001:4860:4860::8844
  ipv6 ifconfig fde4:8dba:82e1:2000:0:0:0:0/56
  ipv6 link-local fe80::1111:1111:1111:1112/64
  no shutdown

It would be nice to check the pcap traces to see if the 1st address is announced correctly or not, then it may be an ofono/modem issue.

History

#1 Updated by pespin 3 months ago

osmo-ggsn seems to be sending the DNS in PCO fine according to pcap trace.

#2 Updated by pespin 3 months ago

Packet forwarded to the MS by sgsn is fine too. the modem or ofono is changing the ip. Maybe the change is done to avoid presenting private address as a DNS?

#3 Updated by pespin 3 months ago

  • Subject changed from wrong first DNS reported in log to ofono: wrong first DNS reported in log

#4 Updated by laforge 3 months ago

Hi Pau,

On Sun, Mar 04, 2018 at 07:31:52PM +0000, pespin [REDMINE] wrote:

Packet forwarded to the MS by sgsn is fine too. the modem or ofono is changing the ip. Maybe the change is done to avoid presenting private address as a DNS?

I highly doubt this is intentional. Almost all operators will hand out private IP addresses
to the mobile phones, and I wouldn't be surprised if many/most also operate their own DNS servers
behind the GGSN. There would be no need for those to be public addresses.

Also, at least with modem modules like those in osmo-gsm-tester, they're
used in machine-to-machine use cases where people sometimes use a
"private APN" that will not have any public internet connectivity.

I suspect this change is unintentional. Maybe the second address is read
twice from an array, rather than 1st + 2nd somewhere in ofono or in the
modem firmware. Looking at QMI traces would help to establish whcih of
the two is faulty. Also, comparing against other modem models gives an
idea if it's more likely ofono or the modem.

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